import java.util.Scanner;


public class Main_yukicoder241 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        int[] a = new int[n];
        boolean flag = true;
        for (int i = 0; i < n; i++) {
        	a[i] = sc.nextInt();
        	if (i > 0 && a[i - 1] != a[i]) {
        		flag = false;
        	}
        }

        if (flag && a[0] < n) {
        	System.out.println(-1);
        } else {
        	int[] ret = new int[n];
        	for (int i = 0; i < n; i++) {
        		ret[i] = i;
        	}

        	for (; true;) {
        		for (int i = 0; i < n; i++) {
        			int r = i + (int)(Math.random() * (n - i));
        			int tmp = ret[i];
        			ret[i] = ret[r];
        			ret[r] = tmp;
        		}

        		boolean check = true;
        		for (int i = 0; i < n; i++) {
        			if (ret[i] == a[i]) {
        				check = false;
        				break;
        			}
        		}
        		
        		if (check) {
        			break;
        		}
        	}

        	for (int i = 0; i < n; i++) {
            	System.out.println(ret[i]);
            }
        }

        sc.close();
    }
}